Rubber impregnated and coated web



E. LIONNE RUBBER IMPREGNATED AND COATED WEB Fil ed Jan. 5, 1936 Jan. 27, 1942.

Nw v v m 2 J material.

Patented Jan. 27, 1942 UNITED. STATES PAT EN'li OFFlCE spasm IMPREGNATED AND ooa'rsn Ernest Lionne, Lynn, Mass. l. I Appiication'lannal'y s, 1930, e l-aim. 51,395 10 claims (Cl. u e) This invention relates to the combined impregnation and coating of porous materials such as textile fabrics with rubber in the initial form of rubberlatex in one operation.

Heretofore in the 'coating of sheet materials, such as textile fabrics, with rubber solutions, that is, a solution of'rubber in a suitable solvent therefor, the tensioned moving web of sheet material has been passed under a coating or spreading knife or bar in front of which is a pool '10 of the coating material which is spread onto the surface of the material by the knife. In this manner a layer of the coating material is deposited on the surface of the web. If the web is a closely woven fabric it can be coated but the coating material because of its relatively high viscosity does not pass into the web' but exists only on the surface of the web. If the web is sufilciently loosely woven it can be impregnated,

that is to "say, the coating material occupies mainly the interstices of the weave but there is relatively no coating of the material on the surface If the web has an open weave the coating material merelypasses through the web without. either impregnating or coating it. Some .weaves, such as those that are not too loosely woven can be impregnated and coated in two successive operations wherein the web isfirst impregnated, and then dried to evaporate the volatile solvent from the impregnating solution '30 and then coated in the manner above described. Furthermore, webs that are loosely woven, as, for instance, textile fabrics of the nature of cheese or tobacco .cloth, cannot be impregnated and coated because the interstices of the weave are so great that they cannot be filled and at the same time receive'and support a surface coating by any commercially practicable single operation known heretofore.

Hence an object of the present invention is a ,40

process, and a machine for carrying out the process, wherein webs of sheet material, and particularly textile fabrics, can be impregnated and coated in one operation by a rubber film forming Inmanyinstances it is not essential that the coated fabric should be at the same time com-' pletely impregnated and for many purposes ity is desirable to have the strands of the fabric covend with a thin film of rubber for bonding the '50 fabric to the coating layer while leaving the interstices ofthe weave, that is to say, the spaces Y between the strands of the fabric, open except at the coated face, where they are traversed by the coating.

'tain the rubber-like particles in condition, and for some purposes a vulcanizing v instance, are suitable mediums.

This is desirable, for instance, in

the waterproofing of fabrics'for raincoats and the like, and the manner in which this result is secured constitutes a further object of the invention.

In the manufacture of raincoats, for instance,

' and especially raincoats for women, it is desirable to employ fabrics having pleasing surface designs'and weaves. Heretofore, however when such fabrics have been treated to render them waterproof, such designs and weaves have deleteriously obscured by the overlying waterproofing material. Hence a further object of the invention is the provision of a waterproof fabric -'the outer or weather surface of which is 'not harmfully covered or obscured by the waterproofing material and wherein the outer surface latex is as transparent as is practicable, although for other purposes the rubber latex may contain a filler or a pigment. Rubber latex is characterized by a high rubber content and low viscosity.

Unconcentrated rubber latex can be obtained having as high as or more of rubber with a. viscosity of not more than four times that of A rubber solution, on the other hand, made by dissolving rubber in a suitable solvent has great viscosityand a much lower rubber content. For some purposes the viscosity ofthe rubberlatex is undesirably low and I increase its viscosity by adding thereto a viscosity increasing medium as amucilase, Karaya gum, casein, for

the rubber film. so that the dry-coated fabric readily n be detachedtherefrom. The surface of the carrier belt preferably is as smooth and bright as is practicable so as to impart to the dispersed 1 surface coating of the supporting belt.

' fabric taken trough and between 7 web a smooth appearance. Preferably the belt is composed of artificial leather having a smooth bright surface coating thereon, which supports the fabric during the process of impregnation and coating. This manner of supporting and treating the fabric constitutes another object of the invention.

The coating and impregnating material is so applied that rubber latex is present mainly in the lower part of the web and between the belt and the fabric so that when the liquid content of the latex is removed a solid continuous sheet of rubber is formed on the lower surface of the web and between it and the belt; Such manner of treating the fabric constitutes a further object of the invention. 1

Another object of the invention is a fabric having on one face thereof a substantially continuous layer of coated material, the material of the layer also existing as thin films around the strands of the fabric but the other surface of the fabric preferably being free from any continuous coating.

A further object of the invention is the conibined and simultaneous impregnation and coating of a fabric by supporting the fabric on a suitable support and applying to the fabric a quantity of the latex that is greater than that which the fibre of the fabric can absorb so that the excess latex will collect in the interstices of the lower part of the fabric and between it and the web and form the coating for the fabric.

A further object of the invention is generally to improve upon coating processes.

Fig. 1 is a diagrammatic view of a coating and impregnating machine constructed for the performance of the process of my invention.

Fig. 2 is a sectional view illustrating in enlarged form the application of the film forming material to the fabric.

Fig. 3 is a view similar to Fig. 2 but illustrat ing a modification where the film forming material is introduced between the fabric and the Fig. 4 is a plan view of a fabric embodying the present invention.

Fig. 5' is an enlarged sectional view of the along line 5-5 of Fig. 4.

Fig. 6 is an enlarged sectional view of the latex containing fabric on the supporting belt.

The coating and impregnating machine form- I heated by suitable means, not'illustrated, to evaporate the volatile constituents of the rubber latex.

portion of a coated The fabric 22 to be coated is contained in a roll 24 and passes from said roll over a supporting roll 26 and preferably first into a conditiona ing tank 28 where it passes under the surface of a liquid bath 30 in said tank and between a plurality of sets of squeez rolls 32 which drive theconditioning liquid into and thus thoroughly impregnates the fabric with the liquid. The

I may consist simply .of water either aloneor containing some reagent which governs the ability of the fabric totake up the rubber latex. The fabric passes out of the .a set of wringer rolls I4 belt in. a greater detail hereinaf said rolls so that the conveyor. belt and the fabric thereon is depressed into a trough-like formation, as is shown in the enlarged view in Fig. 2. .The depth of the trough and hence the degree of pressure exerted on the fabric by the knife can be regulated by adjusting the vertical height of the knife in .a well known manner. The'angle of the knife with respect to the fabric can be adjusted also.

A body or pool 42 of rubber latex is maintained in front of the coating knife and upon the fabric and the belt, latex being constantly added to the body 42 through a pipe 44 from a suitable tank 46,

and into and through the fabric and onto the manner which will be described in The coated and impregnated fabricthence is carried forward by the supporting belt in. For some purposes it may be desirable to provide another coating knife for further spreading on the surface of the fabric and forcing into the fabric the mate'- rial laid thereon by the first knife.

'The wet coated material thence passes with the conveyor belt into the heated drying chamber 20 where the volatile constituents of the rubber latex are evaporated. At the exit of the drying chamber the lower pass of belt passes over a guide roll it. At this point the coated fabric is detached or stripped from the belt and is passed around a guide roll 52 and thence over one or more heated drums 54, two being here shown, that are heated sufliciently high to vulcanize the rubber film. thence passes from the last vulcanizing drum and is wound into a roll 56. Instead of using an unvulcanized latex, which, for vulcanizing, necessitates the drums, or equivalent, a vulcanized latex can more particularly in Figs. particularly to Fig. 6, the damp fabric 22 having the warp strandsA and the weft strands B is sup ported on the upper passof the conveyor belt II on the smooth coated face" thereof and passes under the knife II where the the supporting rollers 40 to form a trough for the pool 42 of latex. The fabric passes beneath the latex pool "and the latex due to its high fluidity passes through the fabric so that at the point where the fabric is directly under the knife the fabric is substantially completely filled with rubber latex, as indicated by the shaded section I. The fabric passes upwardly with the belt out of the trough to the front supporting roll II where the conveyor belt dips between terstices of the trated at the right hand the fabric and between the in Fig. wherein and these films are The latex also collects between too little to obtain the the fabric expands after the rubber latex does not completely fill the inuncompressed fabric. On the the belt the latex settles to fabric, partly by gravity and leaving the knife and horizontal pass of the lower part of the partly by capillary action between the belt and fabric or assumes some such position as illuspart of Fig. 6. The latex also collects under warp strands and the belt by capillary action so that the fabric is upon a thinfilm 62 of rubber latex.

The amount of latex in the interstices of the fabric can be adjusted by adjusting the pressure between the fabric and knife, which adjusts the degree of compression of the fabric and hence the amount of latex that the compressed fabric can accommodate. The amount of rubber in the fabric can be widely adjusted by the-use of latices of different concentrations,

,The belt with the fabric and latex then passes into the evaporating or drying chamber where the moisture content of the rubber latex is dissipated and the rubber filmis formed.

7 A section of the coated fabric is illustrated the fabric 22 has the rubber coating 64 on its bottom face formed by the coagulation of the rubber in the latex film 62. The thickness of the rubber coating is, of course, less than the thickness of the rubber latex under the fabric and on the horizontal pass of the belt due to the evaporation of the liquid content of the latex. The rubber coating 6.4 may have a thickness approximately equal to to of the thickness of the latex layer under the fabric depending upon the proportion of solid matter to liquid in the latex. Thin films 66 of rubber cover the fabric strands in the top face of the fabric integral with the coating 64. The films, however, are so rubber coating readily apparent froma casual inspection of the top surface. Thus the weave of the fabric and the pattern or design thereon is substantially unobscu In the modification illustrated in Figx3'the rubber latex 42a is deposited directly upon the belt under the fabric in front of the knife. The action of the knife is thus to force the rubber latexpositively through the fabric so as to insure thorough penetration of the fabric by the latex. the fabric and the knife so that the fabric passes through the pool of latex. This arrangement is able for impregnating and coating especially closely woven or thick fabrics.

For the coating and'impregnating'of certain webs where the viscosity of the-rubber latex is intended results I may desire to increase the viscosity by,adding to the latex a suitable medium as a mucilage in amounts suflicient to obtain the desired increase in viscos- In passing through the latexpool in front of the coating knife, the strands of the-fabric and the fibres of the strands absorb the latex, the strands at least becoming substantially saturated. The interstices of the fabric also receiveiatex andthe latex in the interstices collects in the lower part of the fabric and between it and the ,supporting belt. It is important that the fabric be treat? ed with more than enough latex than the strands and the excess in part No coating will and fibres can absorb; forms the surface coating.

sometimes desirtice in theperformance of the invention for film begin to appear formed 11 all the latex applied to the fabric can be absorbed by the strands and fibres.

As an example of what is considered good pracmaking waterproof fabric for womens raincoats. percale weighing 100grams per squareyard and having a count of x 80 and a thickness of eight thousandths of an inch, is treated to have deposited thereon and therein 3 to 3 ouncesto grams) of rubber per square yard. The material is entirely waterproof and there is no material evidence of rubber on the outer surface or If the rubber deposit is increased face films are not desired. Aplaid, weighing 47 grams per square yard, and having a count of '16 x '76, and a thickness of seven and one-half thousandths'of an inch, is satisfactorily waterthin that there is noi is in the coating, and in the interstices weave.

' to the fabric in a .q

- and in contact with to obtain a desirable coating,

sheet to form a of from 2 t0 rubaround 3 ounces. 7

It is the cloth itself and not the adjustment of the machine that determines to a considerable extent the amount-of rubber deposited in and on the cloth. If the fabric is of such nature that, the outer face of the fabric has shiny spots indicative of surface films, then the latex which forms these spots has to be removed as by the use of a second knife 50. The amount of rubber latex absorbed by the fabric depends upon many factors such as the weight and haracter of the fabric and the'prior chemical treatment, including printing, that the fabric has received. In general, however, the weight of the fabric is the major factor determining the amount of rubber latex, and consequently rubber absorbed by the fabric and the heavier the fabric the more latex it absorbs. In the examples above given and on the plaid is greater in proportion to the weight of the fabric than with the percale. The plaid, however, has a somewhat lower count and amore open weave than the additional rubber is represented by that part tltlgt of e I claim:

1. The method of coating and impregnating a pervious fabric which comprises conveying the fabric on a horizontaI travelling supporting surface, applying a coating and impregnating liqu'id uantity greater than the fab ric can absorb so that excess liquid collects as a liquid sheet the fabric and travels with the surface and fabric, and drying the liquid soli'd sheet adherent to the fab; ric while the underlying liquid is retained against the fabric by the supporting surface. I Y

2. The methodasin claim 1 wherein the coatl ing and impregnating liquid comprises rubber latex. 1

3, The method of impregnating and coating a pervious fabric which comprises-passing an impregnating and coating liquid ina quantity greater than "the fabric can absorb through the fab-. ric on a'yieldable supporting surface to collect excess 'iquid as a liquid 'sheet' on the surface under e fabric by moving the fabricjhaving an impregnating and coating liquid on its upper sur-' face ,under a spreader knife which exerts pressure thereon, moving the yieldable supporting surface with the fabric to facilitate unitary mov the rubber, deposit in percale so that the on the supporting surface under ment of the liquid sheet and fabric,

and drying the liquid in and under the fabric to form a solid sheet on and adherent to the under face of the coating and impregquantity greater than that which the fibres of the fabric can absorb, forcing the excess latex into and through the fabric to occupy thev interstices of the fabric and collect in the lower part thereof and form a liquid sheet between the fabric and the supporting surface, eliminating the liquid content of the latex to convert the latex in the fabric to solid rubber and the latex in the liquid sheet to a solid sheet which is on the lower face of the fabric and is integral with the rubber in the body of the fabric, and detaching the impregnated and coated fabric from the supportingsurface.

5. That method of producing a rubber coated fabric comprising the steps of simultaneously applying-both an open woven fabric and liquid latex to a yieldable horizontal moving surface to which flcient latex into and through the fabric to form a pool under the fabric, passing the plied fabric the fabric from the surface with the dried rubber coating adhered to the lower side of the fabric.

6. That meth d of producing a rubber coated fabric comprising the steps of moving the fabric and its associated sheet from its supporting surface.

'7. That method of fabric comprising the steps of applying an open fabric to a yieldable moving impervious supporting surface, associating a volume of latex with the upper surface ofthe fabric, moving the producing a rubber coated absorbent pervious fi- I a rubber coating plied fabric and supporting surface underneath spreader means to force the latex into and through the fabric and form a pool underneath the fabric, passing the plied fabric latex and supporting surface through a drying medium to form on the lower surface of the fabric, and removing the fabric and its rubber coat from the supporting surface.

8. The method of simultaneously rubber coating and impregnating an absorbent pervious flbrous fabric on a yieldable smooth impervious supporting surface, which method comprises applying to the upper surface of the fabric rubber latex in a quantity greater than that which'the fibres of the fabric can absorb, forcing the excess latex into and through the fabric tooccupy ric from the the fabric can absorb -ric to form .a pool fabric as a unit the interstices thereof and collect in the lower part of the fabric and form a liquid sheet between the fabric and the supporting surface, passing the plied supporting surface latex pool and fabric as a unit through a drying medium to convert the latex in the fabric to solid rubber and thelatex in the liquid sheet to a solid sheet which is on the lower face of the fabric and .is integral with the rubber in the body of the fabric, and detaching the impregnated and coated fabsupporting surface.

9. The method of coatinga pervious fabric with rubber, which method comprises associating the fabric with a horizontal traveling surface to which a dried film oflatex will not adhere, forming a pool of latex in a quantity greater than the fabric can absorb between the fabric and the supporting surface, moving the pool' of latex and fabric as a unit with the horizontal traveling surface, passing the plied latex pool, fabric and supporting surface as a unit through a drying medium to dry the latex andform an solid rubber sheet adhered to the fabric, and removing the fabric and rubber sheet as a unit from the moving surface.

10. The method of coating a pervious fabric. with rubber, which method comprises associating the fabric with a yieldable horizontal traveling surface to which a dried film of latex will not adhere, drawing the fabric and surface under a spreader, forcing latex in a quantity greater thanv into and through the fabbetween the fabric and the supporting surface, moving the pool of latex and with the horizontal traveling 

